[fix](cup) add keywords KW_PERCENT (#21404)

Or it may cause some edit log replay error, like parsing create routine load stmt, which contains this keyword as
a column name

fe/fe-core/src/main/cup/sql_parser.cup

@@ -7658,6 +7658,8 @@ keyword ::=
     {: RESULT = id; :}
     | KW_PERIOD:id
     {: RESULT = id; :}
+    | KW_PERCENT:id
+    {: RESULT = id; :}
     ;
 
 // Identifier that contain keyword